Urinary System 3 main functions
Elimination of waste products – as urine (95% water, 5% waste)
Regulation of homeostasis
Production of hormones
Organs of the Urinary System
Two kidneys
Two ureters
One urinary bladder
One urethra
Nephrons
The structural and functional unit of the kidneys
Responsible for forming urine through filtration, reabsorption, and secretion
Main structures of the nephrons
Glomerulus – Cluster of blood capillaries
Bowman’s capsules
Composition of Urine
Always contain water, urea, uric acid, creatinine and sodium chloride
Diabetes mellitus – positive glucose urine test
Normal adult excretes approximately 750 to 2000 mL of urine per day
Collection of Urine Specimens
Urine pregnancy testing, require a first-voided, midstream morning specimen
Test for human chorionic gonadotropin (hCG) – review urine and blood tests
Presence of urinary tract infection (UTI), require a clean-catch midstream specimen
Random Specimen
Commonly used for R&M (Routine and Microscopic Urinalysis )
First-Voided Morning Specimen (fasting)
Contains the greatest concentration of dissolved substances
Clean-Catch Midstream Specimen (CCMSU)
Required for culture and bacterial examination – C&S
24-Hour Urine Specimen
Know collection procedure
Measured substances include – Hormones, creatinine/clearance, protein, urea nitrogen
Urine Analyzer
Automatic chemical examination of urine with reagent strips
Refractometer / (Total solids meter)
Specific Gravity determination
Urinometer
Specific Gravity determination
Clinitest done why?
Sugars (Reducing Substances
Acetest done why
Ketone
Sulfosalicylic acid (SSA) done why
Protein
Ictotest done why
Bilirubin
Fecal Occult Blood
Fecal screening to detect small invisible quantities of blood (hemoglobin) in stool
Detect bleeding in the gastrointestinal tract and screen for colon cancer
Require three separate stool samples taken on 3 consecutive days
Should not eat red meat for 3 days prior to the test
Serous fluid composed of?
pericardial, pleural and peritoneal cavities
Blood Glucose
Glucose is the main carbohydrate in blood and the primary source of energy for body cells
It is absorbed by body cells with the intervention of the hormone insulin
Disorders of glucose metabolism:
Diabetes mellitus / hyperglycemia
Hypoglycemia
Glucose Test
Glucose test is most often used in diagnosing and managing diabetes and hypoglycemia
Must specify if specimen is random or fasting
Most laboratories measure serum/plasma glucose levels
Separate serum/plasma from cells ASAP
Blood cells metabolize glucose
Result in false low glucose value
Collect samples in a grey top tube
Potassium oxalate anticoagulant
Sodium fluoride to inhibit glycolysis
Testing methods use the enzymes
Glucose oxidase, hexokinase or glucose dehydrogenase
The reagent strips utilize glucose oxidase
Diabetes and Hypoglycemia —test
Fasting Blood Glucose - (8 – 12 hrs. fast)
(Oral) Glucose Tolerance Test – OGTT –
Post consumption
Random
Urine
HbA1c / glycated hemoglobin – use EDTA whole blood
Quality Assessment – QA / Quality Control - QC
Program to include the evaluation of:
Preanalytical factors
Analytical factors
Postanalytical factors
QC - Accomplished with the use of standards, controls and statistical analysis
Controls – Known, unknown, in-house
Definitions - Accuracy, Precision, Mean Value, Mode, Median
Proficiency testing
QMPLS/IQMH (Quality Management Program Laboratory Services/Institute for Quality Management in Healthcare)
Monitor the proficiency of labs throughout Ontario
Standard Deviation (SD)
Definition and use of SD (1, 2, 3 SD); % within 1SD, 2SD, 3SD
A ± 2 SD limit is commonly used to accept or reject control values
Point-of-Care Testing – POCT
Diagnostic testing at or near the site of patient care
Use small, portable analyzers that give rapid, reliable test results
Analysis include
Hematology, urinalysis, coagulation, chemistry, microbiology and immunological tests
Require a small amount of blood (one or two drops of capillary blood)
Clinical Chemistry Tests
Test performed on blood and other body fluids
Blood and Urine – most commonly tested in Clinical Chemistry laboratory
Review specimen and collection techniques
Specimen must be free from hemolysis
Falsely elevated results – K+, LD, AST, Mg+ , RBC Folate, Vitamin B12
Refrigerate specimen at 40C if testing is delayed
Units of measurement – SI units
Analytes – millimoles per liter – mmol/L
Enzymes – units per liter – U/L
Therapeutic Drugs – often in mg/dl
Electrolytes / “Lytes”
Electrolytes – ions in body fluids
Measurement of electrolytes include:
Na+, K+, Cl-, HCO3-
Maintain fluid and acid-base balance
Trace Elements
Ca, PO4, Mg, Uric Acid
Calcium
Vitamin D is necessary for the absorption and use of calcium
Profiles
Group of tests performed to determine the condition of patients, function of tissues or systems
Profiles include – Kidney/renal, liver/hepatic, cardiac, lipid, thyroid
Therapeutic Drug Screening/Monitoring
To determine the presence or absence of specified drugs or their metabolites
Specimen in Biochemistry lab – blood (serum) and/or urine
Could also include hair, sweat, saliva
Anemia
Biochemistry related tests: (Serum)
Iron, Total Iron Binding Capacity (TIBC), Ferritin, B12 Folate, RBC folate, … (CBC)
RBC folate – EDTA sample
Blood Alcohol Collection
Ethanol, isopropanol, methanol, ethylene glycol, acetone:
No alcohol swab during venipuncture ( e.g. 70% isopropanol, 70% ethanol)
72 Hour Fecal Fat Collection
A normal diet containing about 100 grams of fat per day for 3 days
Sweat Chloride Test
Used to diagnose cystic fibrosis